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16. Rapid ecosystem response to abrupt climate changes during the last glacial period in western Europe, 40-1 6 ka

Author

Wohlfarth, Barbara, Veres, Daniel, Ampel, Linda, Lacourse, Terri, Blaauw, Maarten, Preusser, Frank, Andrieu-Ponel, Valerie, Keravis, Didier, Lallier-Verges, Elisabeth, Bjorck, Svante, Davies, Siwan M., de Beaulieu, Jacques-Louis, Risberg, Jan, Hormes, Anne, Kasper, Haino Uwe, Possnert, Goran, Reille, Maurice, Thouveny, Nicolas, and Zander, Anja

Subjects
Western Europe -- Natural history, Climatic changes -- Influence, Ecosystems -- Evaluation, Lake sediments -- Properties, Heinrich events -- Evaluation, Last Glacial Maximum -- Environmental aspects, Earth sciences
Abstract

We present a high-resolution and independently dated multiproxy lake sediment record from the paleolake at Les Echets in southeastern France that displays synchronous changes in independent limnic and terrestrial ecosystem proxies, in concert with millennial-scale climate oscillations during the last glacial period. Distinct lake-level fluctuations, low lake organic productivity, and open, treeless vegetation indicate cold and dry conditions in response to Heinrich events. Alternating phases of higher and low lake organic productivity, stratified surface waters and long-lasting lake ice cover, decreased or increased catchment erosion, and tree-dominated or herb-dominated vegetation resemble Dansgaard-Oeschger interstadial-stadial variability. Transitions between different ecological states occurred in as little as 40-230 yr and seem to have been controlled by the position of the Polar Front. Ecosystem response after 30 ka suggests that local climate conditions became more important. Our results demonstrate that all parts of the terrestrial system responded to the abrupt and dramatic climatic changes associated with DansgaardOeschger and Heinrich events, and that regional factors modulated ecosystem response. Keywords: lake sediments, paleoenvironmental reconstruction, multiproxy records, DansgaardOeschger cycles, Heinrich events.

Published
2008

19. Innovative methods to monitor rock and mountain slope deformation

Author

Hormes, Anne, primary, Adams, Marc, additional, Amabile, Anna Sara, additional, Blauensteiner, Franz, additional, Demmler, Christian, additional, Fey, Christine, additional, Ostermann, Marc, additional, Rechberger, Christina, additional, Sausgruber, Thomas, additional, Vecchiotti, Filippo, additional, Vick, Louise M., additional, and Zangerl, Christian, additional

Published
2020
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21. Deglaciation of coastal south-western Spitsbergen dated with in situ cosmogenic 10Be and 14C measurements

Author

Young, Nicolás E., Lamp, Jennifer, Koffman, Toby, Briner, Jason P., Schaefer, Joerg, Gjermundsen, Endre F., Linge, Henriette, Zimmerman, Susan, Guilderson, Thomas P., Fabel, Derek, and Hormes, Anne

Abstract

The Svalbard-Barents ice sheet was predominantly a marine-based ice sheet and reconstructing the timing and rate of its decay during the last deglaciation can inform predictions of future decay of marine-based ice sheets (e.g. West Antarctica). Records of ice-sheet change are now routinely built with cosmogenic surface exposure ages, but in some regions, this method is complicated by the presence of isotopic inheritance yielding artificially old and erroneous exposure ages. Here, we present forty-six 1025 Be ages from bedrock (n = 38) and erratic boulders (n = 8) in southwestern Spitsbergen that, when paired\ud with in situ 1427 C measurements (n = 5), constrain the timing of coastal deglaciation following the last\ud glacial maximum. 10Be and 1428 C measurements from bedrock along a ~400 m elevation transect reveal\ud inheritance-skewed 10Be ages, whereas 1429 C measurements constrain 400 m of ice-sheet thinning and\ud coastal deglaciation at 17.4 ± 1.5 ka. Combined with three additional 10Be-dated coastal sites, we show that the southwestern margin of the Svalbard-Barents ice sheet retreated out of Norwegian Sea\ud between ~18-16 ka. In situ 1432 C measurements can provide key chronological information on ice-sheet response to the last termination in cases where measurements of long-lived nuclides are compromised by isotopic inheritance.

Published
2018

22. Remote Identification, Characterization and Monitoring of Erosional Processes

Author

Salazar, Sean E., Hormes, Anne, and Issler, Dieter

Abstract

Remote sensing techniques and geophysical techniques have enabled the collection of vital information on geotechnical, hydrogeological, and environmental processes. These techniques may offer improvements over traditional data collection techniques or may provide data not readily available using conventional instrumentation. An assessment of various remote sensing and geophysical techniques, used to collect parameters of interest to the Multi-scale Erosion Risk under Climate Change (MERRIC) project, is provided in this technical note. This technical note is a deliverable of the MERRIC work package 4 on "Warning, monitoring, and non-physical mitigation measures". A list of 11 key parameters for coastal erosion studies was established and matched with appropriate remote sensing techniques (including microwave, laser, and optical techniques) and on- and off-shore (or near-shore) geophysical techniques. The characteristics of each of the techniques is listed and background material is provided. The maturity of these techniques is described through examples in the literature and the potential for application within the scope of MERRIC is discussed. Many of the more mature techniques described in this technical note (for example, terrestrial lidar scanning [TLS], or electrical resistivity tomography [ERT]) are already routinely used in NGI projects, and thus, their relevance for MERRIC is well understood. Other emerging techniques (for example, terrestrial radar interferometry, or multi-beam echo sounding [MBES]) are less commonly applied, but may nonetheless prove to be indispensable for future projects related to MERRIC. It is, therefore, recommended that the potential of emergent remote sensing and geophysical techniques will be further investigated using the resources available at NGI.

Published
2018

24. Holocene multi-proxy environmental reconstruction from Lake Hakluytvatnet, Amsterdamøya Island, Svalbard (79.5°N)

Author

Gjerde, Martha, Bakke, Jostein, D'Andrea, William, Balascio, Nicholas, Bradley, Raymond, Vasslog, Kristian, Olafsdottir, Saedis, Rother, Torgeir, Perren, Bianca, Hormes, Anne, Gjerde, Martha, Bakke, Jostein, D'Andrea, William, Balascio, Nicholas, Bradley, Raymond, Vasslog, Kristian, Olafsdottir, Saedis, Rother, Torgeir, Perren, Bianca, and Hormes, Anne

Abstract

High resolution proxy records of past climate are sparse in the Arctic due to low organic production that restricts the use of radiocarbon dating and challenging logistics that make data collection difficult. Here, we present a new lake record from lake Hakluytvatnet at Amsterdamøya island (79.5°N), the northwesternmost island on Svalbard. Multi-proxy analyses of lake sediments in combination with geomorphological mapping reveal large environmental shifts that have taken place at Amsterdamøya during the Holocene. A robust chronology has been established for the lake sediment core through 28 AMS radiocarbon ages, and this gives an exceptionally well-constrained age control for a lake at this latitude. The Holocene was a period with large changes in the Hakluytvatnet catchment, and the onset of the Neoglacial (ca. 5 ka) marks the start of modern-day conditions in the catchment. The Neoglacial is characterized by fluctuations in the minerogenic input to the lake as well as internal productivity, and we suggest that these fluctuations are driven by atmospherically forced precipitation changes as well as sea ice extent modulating the amount of moisture that can reach Hakluytvatnet.

Published
2018

27. A global multiproxy database for temperature reconstructions of the Common Era

Author

UCL - SST/ELI/ELIC - Earth & Climate, Emile-Geay, Julien, McKay, Nicholas P., Kaufman, Darrell S., von Gunten, Lucien, Wang, Jianghao, Anchukaitis, Kevin J., Abram, Nerilie J., Addison, Jason A., Curran, Mark A.J., Evans, Michael N., Henley, Benjamin J., Hao, Zhixin, Martrat, Belen, McGregor, Helen V., Neukom, Raphael, Pederson, Gregory T., Stenni, Barbara, Thirumalai, Kaustubh, Werner, Johannes P., Xu, Chenxi, Divine, Dmitry V., Dixon, Bronwyn C., Gergis, Joelle, Mundo, Ignacio A., Nakatsuka, Takeshi, Phipps, Steven J., Routson, Cody C., Steig, Eric J., Tierney, Jessica E., Tyler, Jonathan J., Allen, Kathryn J., Bertler, Nancy A.N., Björklund, Jesper, Chase, Brian M., Chen, Min-Te, Cook, Ed, de Jong, Rixt, DeLong, Kristine L., Dixon, Daniel A., Ekaykin, Alexey A., Ersek, Vasile, Filipsson, Helena L., Francus, Pierre, Freund, Mandy B., Frezzotti, Massimo, Gaire, Narayan P., Gajewski, Konrad, Ge, Quansheng, Goosse, Hugues, Gornostaeva, Anastasia, Grosjean, Martin, Horiuchi, Kazuho, Hormes, Anne, Husum, Katrine, Isaksson, Elisabeth, Kandasamy, Selvaraj, Kawamura, Kenji, Kilbourne, K. Halimeda, Koç, Nalan, Leduc, Guillaume, Linderholm, Hans W., Lorrey, Andrew M., Mikhalenko, Vladimir, Mortyn, P. Graham, Motoyama, Hideaki, Moy, Andrew D., Mulvaney, Robert, Munz, Philipp M., Nash, David J., Oerter, Hans, Opel, Thomas, Orsi, Anais J., Ovchinnikov, Dmitriy V., Porter, Trevor J., Roop, Heidi A., Saenger, Casey, Sano, Masaki, Sauchyn, David, Saunders, Krystyna M., Seidenkrantz, Marit-Solveig, Severi, Mirko, Shao, Xuemei, Sicre, Marie-Alexandrine, Sigl, Michael, Sinclair, Kate, St. George, Scott, St. Jacques, Jeannine-Marie, Thamban, Meloth, Kuwar Thapa, Udya, Thomas, Elizabeth R., Turney, Chris, Uemura, Ryu, Viau, Andre E., Vladimirova, Diana O., Wahl, Eugene R., White, James W.C., Yu, Zicheng, Zinke, Jens, UCL - SST/ELI/ELIC - Earth & Climate, Emile-Geay, Julien, McKay, Nicholas P., Kaufman, Darrell S., von Gunten, Lucien, Wang, Jianghao, Anchukaitis, Kevin J., Abram, Nerilie J., Addison, Jason A., Curran, Mark A.J., Evans, Michael N., Henley, Benjamin J., Hao, Zhixin, Martrat, Belen, McGregor, Helen V., Neukom, Raphael, Pederson, Gregory T., Stenni, Barbara, Thirumalai, Kaustubh, Werner, Johannes P., Xu, Chenxi, Divine, Dmitry V., Dixon, Bronwyn C., Gergis, Joelle, Mundo, Ignacio A., Nakatsuka, Takeshi, Phipps, Steven J., Routson, Cody C., Steig, Eric J., Tierney, Jessica E., Tyler, Jonathan J., Allen, Kathryn J., Bertler, Nancy A.N., Björklund, Jesper, Chase, Brian M., Chen, Min-Te, Cook, Ed, de Jong, Rixt, DeLong, Kristine L., Dixon, Daniel A., Ekaykin, Alexey A., Ersek, Vasile, Filipsson, Helena L., Francus, Pierre, Freund, Mandy B., Frezzotti, Massimo, Gaire, Narayan P., Gajewski, Konrad, Ge, Quansheng, Goosse, Hugues, Gornostaeva, Anastasia, Grosjean, Martin, Horiuchi, Kazuho, Hormes, Anne, Husum, Katrine, Isaksson, Elisabeth, Kandasamy, Selvaraj, Kawamura, Kenji, Kilbourne, K. Halimeda, Koç, Nalan, Leduc, Guillaume, Linderholm, Hans W., Lorrey, Andrew M., Mikhalenko, Vladimir, Mortyn, P. Graham, Motoyama, Hideaki, Moy, Andrew D., Mulvaney, Robert, Munz, Philipp M., Nash, David J., Oerter, Hans, Opel, Thomas, Orsi, Anais J., Ovchinnikov, Dmitriy V., Porter, Trevor J., Roop, Heidi A., Saenger, Casey, Sano, Masaki, Sauchyn, David, Saunders, Krystyna M., Seidenkrantz, Marit-Solveig, Severi, Mirko, Shao, Xuemei, Sicre, Marie-Alexandrine, Sigl, Michael, Sinclair, Kate, St. George, Scott, St. Jacques, Jeannine-Marie, Thamban, Meloth, Kuwar Thapa, Udya, Thomas, Elizabeth R., Turney, Chris, Uemura, Ryu, Viau, Andre E., Vladimirova, Diana O., Wahl, Eugene R., White, James W.C., Yu, Zicheng, and Zinke, Jens

Abstract

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850–2014. Global temperature composites show a remarkable degree of coherence between high- and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.

Published
2017

28. A global multiproxy database for temperature reconstructions of the Common Era

Author

Emile-Geay, Julien, McKay, Nicholas P., Kaufman, Darrell S., von Gunten, Lucien, Wang, Jianghao, Anchukaitis, Kevin J., Abram, Nerilie J., Addison, Jason A., Curran, Mark A.J., Evans, Michael N., Henley, Benjamin J., Hao, Zhixin, Martrat, Belen, McGregor, Helen V., Neukom, Raphael, Pederson, Gregory T., Stenni, Barbara, Thirumalai, Kaustubh, Werner, Johannes P., Xu, Chenxi, Divine, Dmitry V., Dixon, Bronwyn C., Gergis, Joelle, Mundo, Ignacio A., Nakatsuka, Takeshi, Phipps, Steven J., Routson, Cody C., Steig, Eric J., Tierney, Jessica E., Tyler, Jonathan J., Allen, Kathryn J., Bertler, Nancy A.N., Björklund, Jesper, Chase, Brian M., Chen, Min-Te, Cook, Ed, de Jong, Rixt, DeLong, Kristine L., Dixon, Daniel A., Ekaykin, Alexey A., Ersek, Vasile, Filipsson, Helena L., Francus, Pierre, Freund, Mandy B., Frezzotti, Massimo, Gaire, Narayan P., Gajewski, Konrad, Ge, Quansheng, Goosse, Hugues, Gornostaeva, Anastasia, Grosjean, Martin, Horiuchi, Kazuho, Hormes, Anne, Husum, Katrine, Isaksson, Elisabeth, Kandasamy, Selvaraj, Kawamura, Kenji, Kilbourne, K. Halimeda, Koç, Nalan, Leduc, Guillaume, Linderholm, Hans W., Lorrey, Andrew M., Mikhalenko, Vladimir, Mortyn, P. Graham, Motoyama, Hideaki, Moy, Andrew D., Mulvaney, Robert, Munz, Philipp M., Nash, David J., Oerter, Hans, Opel, Thomas, Orsi, Anais J., Ovchinnikov, Dmitriy V., Porter, Trevor J., Roop, Heidi A., Saenger, Casey, Sano, Masaki, Sauchyn, David, Saunders, Krystyna M., Seidenkrantz, Marit-Solveig, Severi, Mirko, Shao, Xuemei, Sicre, Marie-Alexandrine, Sigl, Michael, Sinclair, Kate, St. George, Scott, St. Jacques, Jeannine-Marie, Thamban, Meloth, Kuwar Thapa, Udya, Thomas, Elizabeth R., Turney, Chris, Uemura, Ryu, Viau, Andre E., Vladimirova, Diana O., Wahl, Eugene R., White, James W.C., Yu, Zicheng, Zinke, Jens, Emile-Geay, Julien, McKay, Nicholas P., Kaufman, Darrell S., von Gunten, Lucien, Wang, Jianghao, Anchukaitis, Kevin J., Abram, Nerilie J., Addison, Jason A., Curran, Mark A.J., Evans, Michael N., Henley, Benjamin J., Hao, Zhixin, Martrat, Belen, McGregor, Helen V., Neukom, Raphael, Pederson, Gregory T., Stenni, Barbara, Thirumalai, Kaustubh, Werner, Johannes P., Xu, Chenxi, Divine, Dmitry V., Dixon, Bronwyn C., Gergis, Joelle, Mundo, Ignacio A., Nakatsuka, Takeshi, Phipps, Steven J., Routson, Cody C., Steig, Eric J., Tierney, Jessica E., Tyler, Jonathan J., Allen, Kathryn J., Bertler, Nancy A.N., Björklund, Jesper, Chase, Brian M., Chen, Min-Te, Cook, Ed, de Jong, Rixt, DeLong, Kristine L., Dixon, Daniel A., Ekaykin, Alexey A., Ersek, Vasile, Filipsson, Helena L., Francus, Pierre, Freund, Mandy B., Frezzotti, Massimo, Gaire, Narayan P., Gajewski, Konrad, Ge, Quansheng, Goosse, Hugues, Gornostaeva, Anastasia, Grosjean, Martin, Horiuchi, Kazuho, Hormes, Anne, Husum, Katrine, Isaksson, Elisabeth, Kandasamy, Selvaraj, Kawamura, Kenji, Kilbourne, K. Halimeda, Koç, Nalan, Leduc, Guillaume, Linderholm, Hans W., Lorrey, Andrew M., Mikhalenko, Vladimir, Mortyn, P. Graham, Motoyama, Hideaki, Moy, Andrew D., Mulvaney, Robert, Munz, Philipp M., Nash, David J., Oerter, Hans, Opel, Thomas, Orsi, Anais J., Ovchinnikov, Dmitriy V., Porter, Trevor J., Roop, Heidi A., Saenger, Casey, Sano, Masaki, Sauchyn, David, Saunders, Krystyna M., Seidenkrantz, Marit-Solveig, Severi, Mirko, Shao, Xuemei, Sicre, Marie-Alexandrine, Sigl, Michael, Sinclair, Kate, St. George, Scott, St. Jacques, Jeannine-Marie, Thamban, Meloth, Kuwar Thapa, Udya, Thomas, Elizabeth R., Turney, Chris, Uemura, Ryu, Viau, Andre E., Vladimirova, Diana O., Wahl, Eugene R., White, James W.C., Yu, Zicheng, and Zinke, Jens

Abstract

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all continental regions and major ocean basins. The records are from trees, ice, sediment, corals, speleothems, documentary evidence, and other archives. They range in length from 50 to 2000 years, with a median of 547 years, while temporal resolution ranges from biweekly to centennial. Nearly half of the proxy time series are significantly correlated with HadCRUT4.2 surface temperature over the period 1850-2014. Global temperature composites show a remarkable degree of coherence between high-and low-resolution archives, with broadly similar patterns across archive types, terrestrial versus marine locations, and screening criteria. The database is suited to investigations of global and regional temperature variability over the Common Era, and is shared in the Linked Paleo Data (LiPD) format, including serializations in Matlab, R and Python.

Published
2017

29. Climate variability in subarctic area for the last two millennia

Author

Nicolle, Marie, primary, Debret, Maxime, additional, Massei, Nicolas, additional, Colin, Christophe, additional, deVernal, Anne, additional, Divine, Dmitry, additional, Werner, Johannes P., additional, Hormes, Anne, additional, Korhola, Atte, additional, and Linderholm, Hans W., additional

Published
2017
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31. Experience in using a Learning Management System (Göteborgs Universitets Lärplattform - GUL) for integrated course design

Author

Hormes, Anne

Subjects
Samfunnsvitenskap: 200::Pedagogiske fag: 280 [VDP], ComputingMilieux_COMPUTERSANDEDUCATION, Universitetspedagogikk
Abstract

Integrated course design needs a developed structure based on pedagogic principles in order to keep track of learning outcomes, assignments, learning resources and lectures. A Learning Management System (LMS) is tested for the learning outcome experience of 24 students that took a Quaternary Geology course at University of Gothenburg. A student survey with a questionnaire and a personal feedback session were analyzed in order to receive objective criteria to evaluate the usefulness of the LMS for the distribution of learning resources. As a key finding students will need to be exposed in hands-on exercises to the LMS in order to take full advantage of the offered online information and resources.

Published
2015

33. Constraining the chronology of Pleistocene glaciations on Svalbard : Kapp Ekholm re-visited

Author

Eccleshall, Sarah V., Hormes, Anne, Hovland, Alexander, Preusser, Frank, Eccleshall, Sarah V., Hormes, Anne, Hovland, Alexander, and Preusser, Frank

Abstract

The Kapp Ekholm site, in central Spitsbergen, shows alternating units of glaciomarine sandy silt and diamicton representing three glacial cycles and is key in reconstructing the Late Pleistocene glacial history of Svalbard. Part of the site is reinvestigated here by focusing on re-dating two units (B and F) interpreted as interglacial/interstadial glaciomarine deposits, in order to constrain the controversial chronology. A combination of Optical Stimulated Luminescence (OSL) on quartz, infrared stimulated luminescence with a 50 degrees C readout temperature (IRSL50) and post infrared-infrared stimulated luminescence (pIR), both on feldspar, was applied. While Formation B was beyond the dateable range of OSL, IRSL50 and pIR ages lead to the conclusion that this unit represents the Last Interglacial, Marine Isotope Stage (MIS) 5e, and the underlying diamicton the MIS 6 glacial. Formation F yielded ages implying that the formation represents the MIS 5a interstadial and the underlying diamicton is interpreted to represent the MIS 5b stadial. This agrees with conclusions drawn concerning the Pleistocene glaciations elsewhere on Svalbard.

Published
2016
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34. Constraining the chronology of Pleistocene glaciations on Svalbard: Kapp Ekholm re-visited

Author

Eccleshall, Sarah, Hormes, Anne, Hovland, Alexander, Preusser, Frank, Eccleshall, Sarah, Hormes, Anne, Hovland, Alexander, and Preusser, Frank

Abstract

The Kapp Ekholm site, in central Spitsbergen, shows alternating units of glaciomarine sandy silt and diamicton representing three glacial cycles and is key in reconstructing the Late Pleistocene glacial history of Svalbard. Part of the site is reinvestigated here by focusing on re-dating two units (B and F) interpreted as interglacial/interstadial glaciomarine deposits, in order to constrain the controversial chronology. A combination of Optical Stimulated Luminescence (OSL) on quartz, infrared stimulated luminescence with a 50 °C readout temperature (IRSL50) and post infrared-infrared stimulated luminescence (pIR), both on feldspar, was applied. While Formation B was beyond the dateable range of OSL, IRSL50 and pIR ages lead to the conclusion that this unit represents the Last Interglacial, Marine Isotope Stage (MIS) 5e, and the underlying diamicton the MIS 6 glacial. Formation F yielded ages implying that the formation represents the MIS 5a interstadial and the underlying diamicton is interpreted to represent the MIS 5b stadial. This agrees with conclusions drawn concerning the Pleistocene glaciations elsewhere on Svalbard.

Published
2016

38. Deglaciation of coastal south‐western Spitsbergen dated with in situ cosmogenic 10Be and 14C measurements.

Author

Young, Nicolás E., Lamp, Jennifer, Koffman, Toby, Briner, Jason P., Schaefer, Joerg, Gjermundsen, Endre F., Linge, Henriette, Zimmerman, Susan, Guilderson, Thomas P., Fabel, Derek, and Hormes, Anne

Subjects
GLACIAL melting, COSMOGENIC nuclides, CARBON isotopes, BERYLLIUM isotopes, ICE sheets
Abstract

The Svalbard–Barents ice sheet was predominantly a marine‐based ice sheet and reconstructing the timing and rate of its decay during the last deglaciation informs predictions of future decay of marine‐based ice sheets (e.g. West Antarctica). Records of ice‐sheet change are routinely built with cosmogenic surface exposure ages, but in some regions, this method is complicated by the presence of isotopic inheritance yielding artificially old and erroneous exposure ages for the most recent deglaciation. We present 46 10Be ages from south‐western Spitsbergen that, when paired with in situ14C measurements (n = 5), constrain the timing of coastal deglaciation following the last glacial maximum. 10Be and in situ14C measurements from bedrock along a ∼400‐m elevation transect reveal inheritance‐skewed 10Be ages, whereas in situ14C measurements constrain 400 m of ice‐sheet thinning and coastal deglaciation at 17.4 ± 1.5 ka. Our in situ14C‐dated transect, combined with three additional 10Be‐dated coastal sites, show that the south‐western margin of the Svalbard–Barents ice sheet retreated out of the Norwegian Sea between ∼18 and 16 ka. In situ14C measurements provide key chronological information on ice‐sheet response to the last termination in cases where measurements of long‐lived nuclides are compromised by isotopic inheritance. [ABSTRACT FROM AUTHOR]

Published
2018
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42. Climate variability in subarctic area for the last two millennia.

Author

Nicolle, Marie, Debret, Maxime, Massei, Nicolas, Colin, Christophe, deVernal, Anne, Divine, Dmitry, Werner, Johannes P., Hormes, Anne, Korhola, Atte, and Linderholm, Hans W.

Abstract

To put in perspective the recent climate change, it is necessary to extend the instrumental climate records with proxy data from palaeoclimate archives. Arctic climate variability for the last two millennia has been investigated using statistical and signal analyses from three regionally averaged records from the North Atlantic, Siberia and Alaska based on many sort of proxy data archived in the Arctic 2k database. In the North Atlantic and Alaska areas, the major climatic trend is characterized by long-term cooling interrupted by the recent warming that started at the beginning of the 19th century. This cooling trend is not clearly visible in the Siberian region. The Little Ice Age (LIA) was identified from the individual series and is characterized by an important spatial and temporal expression of climate variability. It started at the earliest by around 1200 AD and ended at the latest in the middle of the 20th century. The large spread temporal coverage of LIA did not show regional consistency or particular spatial distribution and did not show relationship with archive/proxy type either. A focus on the last two centuries shows a recent warming characterized by a well-marked warming trend paralleling with increasing greenhouse gas emissions. It also shows a multi-decadal variability likely due to natural processes acting on the internal climate system variability at regional scale. A 16-30 years cycle is found in Alaska and seems to be linked to the Pacific Decadal Oscillation (PDO) whereas ~ 20-30 and ~ 50-90 years periodicities characterize the North Atlantic climate regime, likely in relation with the Atlantic Multidecadal Oscillation (AMO). These regional features are apparently linked to the sea-ice cover fluctuations through ice-temperature positive feedback. [ABSTRACT FROM AUTHOR]

Published
2017
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44. Age, origin and significance of a new middle MIS 3 tephra horizon identified within a long-core sequence from Les Echets, France

Author

Veres, Daniel, Davies, Siwan M., Wohlfarth, Barbara, Preusser, Frank, Wastegård, Stefan, Ampel, Linda, Hormes, Anne, Possnert, Göran, Raynal, Jean-Paul, Vernet, Gerard, Veres, Daniel, Davies, Siwan M., Wohlfarth, Barbara, Preusser, Frank, Wastegård, Stefan, Ampel, Linda, Hormes, Anne, Possnert, Göran, Raynal, Jean-Paul, and Vernet, Gerard

Abstract

A new tephra has been identified within a long core (EC 3) sequence recovered from Les Echets, near Lyon, France. This visible tephra was discovered as part of a high resolution multiproxy re-investigation of the Les Echets sequence. Independent chronological information suggests that the tephra is c. 2 000-45 000 years old, and geochemical analysis indicates that it is of basanitic composition. The latter suggests a possible origin in the Eifel, however, as yet, no other volcanic events or deposits can be correlated to the Les Echets tephra. New sedimentological and chronological data are presented indicating that the tephra falls within an interval that most likely correlates with Dansgaard-Oeschger events 12-9. Thus, this tephra could potentially be an important middle MIS 3 marker horizon in central Europe if it can be traced in other palaeorecords.

Published
2008
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45. Rapid ecosystem response to abrupt climate changes during the last glacial period in western Europe, 40-16 ka

Author

Wohlfarth, Barbara, Veres, Daniel, Ampel, Linda, Lacourse, Terri, Blaauw, Maarten, Preusser, Frank, Andrieu-Ponel, Valerie, Keravis, Didier, Lallier-Verges, Elisabeth, Björck, Svante, Davies, Siwan M., de Beaulieu, Jacques-Louis, Risberg, Jan, Hormes, Anne, Kasper, Haino Uwe, Possnert, Göran, Reille, Maurice, Thouveny, Nicolas, Zander, Anja, Wohlfarth, Barbara, Veres, Daniel, Ampel, Linda, Lacourse, Terri, Blaauw, Maarten, Preusser, Frank, Andrieu-Ponel, Valerie, Keravis, Didier, Lallier-Verges, Elisabeth, Björck, Svante, Davies, Siwan M., de Beaulieu, Jacques-Louis, Risberg, Jan, Hormes, Anne, Kasper, Haino Uwe, Possnert, Göran, Reille, Maurice, Thouveny, Nicolas, and Zander, Anja

Abstract

We present a high-resolution and independently dated multiproxy lake sediment record from the paleolake at Les Echets in southeastern France that displays synchronous changes in independent limnic and terrestrial ecosystem proxies, in concert with millennial-scale climate oscillations during the last glacial period. Distinct lake-level fluctuations, low lake organic productivity, and open, treeless vegetation indicate cold and dry conditions in response to Heinrich events. Alternating phases of higher and low lake organic productivity, stratified surface waters and long-lasting lake ice cover, decreased or increased catchment erosion, and tree-dominated or herb-dominated vegetation resemble Dansgaard-Oeschger interstadial-stadial variability. Transitions between different ecological states occurred in as little as 40-230 yr and seem to have been controlled by the position of the Polar Front. Ecosystem response after 30 ka suggests that local climate conditions became more important. Our results demonstrate that all parts of the terrestrial system responded to the abrupt and dramatic climatic changes associated with Dansgaard-Oeschger and Heinrich events, and that regional factors modulated ecosystem response.

Published
2008
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46. A geochronological approach to understanding the role of solar activity on Holocene glacier length variability in the Swiss Alps

Author

Hormes, Anne, Beer, Jürg, Schluechter, Christian, Hormes, Anne, Beer, Jürg, and Schluechter, Christian

Abstract

We present a radiocarbon data set of 71 samples of wood and peat material that melted out or sheared out from underneath eight presentday mid-latitude glaciers in the Central Swiss Alps. Results indicated that in the past several glaciers have been repeatedly less extensive than they were in the 1990s. The periods when glaciers had a smaller volume and shorter length persisted between 320 and 2500 years. This data set provides greater insight into glacier variability than previously possible, especially for the early and middle Holocene. The radiocarbon-dated periods defined with less extensive glaciers coincide with periods of reduced radio-production, pointing to a connection between solar activity and glacier melting processes. Measured long-term series of glacier length variations show significant correlation with the total solar irradiance. Incoming solar irradiance and changing albedo can account for a direct forcing of the glacier mass balances. Long-term investigations of atmospheric processes that are in interaction with changing solar activity are needed in order to understand the feedback mechanisms with glacier mass balances.

Published
2006
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